No abstract

This work deals with the application of ozonated water for the BEOL stripping of DUV-resists. For this purpose analytical techniques for the quantification of molecular O3 in the water as well as methods for the non-destructive analysis of resists on wafers have been studied. The aim is to be able to determine the concentrations of O3, its decomposition, under the influence of various parameters, and to correlate these data with the polymer structure of the resist on the wafer and the efficiency of resist removal.

In the process of resist stripping by DI/O 3 (ozonated DI-water) there are 2 principal active species of interest: the molecular O 3 in a reaction which is a classical ozonolysis and the radicals generated by the decomposition of O 3 in DI-water with their classical reaction patterns. Whereas O 3 is easily detected in the UV/Vis region the quantification of radicals is much more complicated. Therefore a part of this work deals with the evaluation of methods for the radical determination. As the ratio of radicals to O 3 varies with the conditions (pH, temperature etc.) resist stripping efficiency has been investigated with different additives on high dose arsenic implanted (As 5 keV 10 15 [cm -2 ], As 40 keV 10 16 [cm -2 ]) resists. The resist thinning process has also been studied with the help of profilometric measurements and optical microscopy. Experimental DetailsRadical determination Radical trapping. The radicals produced during the decomposition of the O 3 in DIwater were trapped using two separate methods, one with MeOH (1) for trapping and the other with DMSO (2),